New GPU (GTX 1080), peaks at 50% usage

[derodo]

Hi,

 

I know there is another thread regarding something similar, but it's quite old (from the 1.5.2 era), so I just thought to create a new one.

 

This is the thing: I have an i7 3770K (16GB DDR3 + SSD), and upgraded from an ATI HD7650, to an nVidia GTX 1080.

 

With the ATI, I got the GPU at 100% usage, and the CPU was around 20-30%; so I thought upgrading the GPU would help...

 

But things are a bit weird; after upgrading, things haven't got as much better as I expected. The GPU stays around 30% usage, and the CPU at 30% as well (all of the cores, not just one stuck at 100%). It's weird...like DCS is not actually pushing the GPU, nor the CPU either...

 

...for the other game I tested (I just installed the 1080), the difference was HUGE; went from crappy FPS to outstanding steady 60+. So I was just smiling inside...waitingto see how DCS would perform...launched it...setup a sample mission and...wtf?!?! :)

 

...is anyone having this same issue? Maybe it got fixed on the 2.2 Open Beta?

[lanmancz]

Keep in mind that "30% overall usage" means that the OS is switching the DCS threads between cores automatically unless you lock it to a single core (bad idea). You will never see a single/double thread process to fully utilize the CPU (it can't as it would need at least 4 threads to do that) and as the OS switches the threads around the result is this kind of utilization. But for a single/dual thread process like DCS this pretty much means 100% utilization as this averages out as ~30% utilization of each core over the 1s measurement interval as it's being switched around by the OS. AFAIK (unless something changed) DCS uses 2 threads - one for everything except sound and the other for sound (probably not as demanding). This will probably not change until they implement DX12 or Vulkan (probably that according to rumors) which can utilize multiple cores for rendering as currently all rendering is done in a single thread (no way around that). So my guess is that you're CPU limited (single thread performance limit) to fully utilize that 1080 of yours, especially if not OC'd. DCS is way more CPU intensive than the other game you tested probably because it has to wait for the physics computations to be done before rendering (in the single thread), hence the longer frame rendering time -> lower FPS. That would explain it. I guess you could crank up some GPU options like anti-aliasing etc. that don't need to wait for CPU to utilize the card more. You will not see any more FPS increase with options that require CPU (object density etc.) as you're already CPU limited.

Edited December 25, 2017 by lanmancz

[derodo]

Yeah kind of figured that out and finally "isolated and solved" the problem.

 

I was reluctant to think it could be a CPU bottleneck (as I read on other posts), but that's what it was...a kind of "hidden" CPU bottleneck having to do with in-game object management.

 

Just dialing down the tree draw distance (which I nahively maxed right away :) gave me 60+ FPS and everything is super smooth now (peaking at 150-200fps).

 

CPU & GPU usage is more or less the same (not above 40%), and I can't get past 50% of the tree draw distance slider without suffering a lot of FPS drops.

 

As lanmancz said, CPU at 30% might simply mean one core is at 100% while the others are almost idling; which is exactly what was going on. It dind't look that way looking at the performance monitor, but the tree count test kind of proved it has something to do with the CPU not being optimally used.

 

Anyway, I'm quite happy so far; I can now play with everything else maxed out and have spare GPU power for VR :)

 

Let's hope 2.5 and SpeedTree alleviate the issue even more (which I think it does from what I've read).

[Art-J]

You didn't specify which game version you're talking about. 1.5.x doesn't utilize modern cards well no matter how fast CPU you have, so up to 50% sounds OK.

 

2.x.x does, however, so even with CPU bottleneck, you should be getting more GPU usage reported there.

[xoxen]

Hi, somtimes I also have the feeling my PC does not give everything he would be capable to do. I recently figured out that deleting the shader folder in saved games brought me 15 FPS more. Didn't check the usage but I was happy to figure this out. At least worth giving it a try. The exact name of the folder is metashaders or something like that. It will be build up from DCS again.

Take care,

Xoxen

Edited December 26, 2017 by xoxen

[derodo]

Yeah the shader folder deletion trick was the first thing I did :) Didn't get any better though.

 

It's just this CPU bottleneck. Will have to deal with it until 2.5 comes out and hope for the best (I'm sticking with 1.5.x in the mean time).

[fudabidu]

I've permanently assigned DCS to cores 0 & 1 and assigned everything else that might run in parallel with DCS to 2 & 3 (TS, SRS, TIR, Winamp..).

 

I'm just running an i5 @3.3 and an R9 380, so your milage may vary, but I gained about 20% FPS just by doing that.

 

This is with 1.5, but the 2-core limitation is still in place with 2.x, so it's worth a shot until this limit finally goes.

[kiss4luna]

I have 6700K and Titan Xp and everything maxed, GPU utility is 98% and framerate around 60. Maybe something about your settings?

[Cibit]

I never got very high GPU usage with an old locked i5@ 3.6 but changing to an 8600k@5.2 enables the card to run at close to 100% in 2.2 and the CPU barely breaks sweat. New CPU/mobo will see you get the best out of your card.:)